Heat a large pot of water to boiling. Meanwhile, peel potatoes and cut into quarters. Add to boiling water with salt. Boil 20 minutes, or until tender. Drain well.

Preheat the oven to 400ø. Coat a 2-qt. casserole dish with nonstick cooking spray. Set aside.

Mash potatoes coarsely with a fork or a potato masher. Transfer to the prepared casserole dish, smoothing the top with a spatula.

Prepare rum glaze: Melt butter in a medium-sized, heavy skillet. Stir in sugar and lemon juice and cook over medium-high heat 3 minutes, or until bubbly. Add rum, return the mixture to a boil, and pour over sweet potatoes.

Bake 45 minutes, or until the glaze has become slightly crusty and nicely golden. Cool for 5 minutes. Makes 12 servings.